Hi:

I have an MTD riding lawn mower, 18hp, 42" cut, 7 speed.
1. When the mower starts - No problem.
2. When I engage the blades with the mower in a fixed position,
Brake on, neutral position; No problem.
3. When I start riding the mower in the forward position, with any speed
Setting, I hear a screeching sound, like metal striking metal.
It’s not continual. It comes and goes, but, for the most part it's there.
4. When I ride the mower in reverse, no screeching sound is heard.

Thanks for any help/info. - Nad -

This may be hard to check since the mower needs to move tosee/haer the problem. Jack up both rear wheels with a good jack that allows the wheels to remain free and try to recreate the sound. I think you should concentrate on the idler pulley and the spring loaded tensioner.One of those pulleys is rubbing the armit is mounted to.

Ball could be correct, and we recently worked on two different mtds that the rear idler pulley was rubbing against the units right rear body itself. You should be able to see a shiny spot where the rubbing is occurring. And as ball... stated, check the idler pulleys for wear, the bearings are probably going bad and will end up not only costing you for a new pulley(s), but a belt(s) as well if a pulley locks up on you.